The main intention of the present is to reduce electromagnetic interference (EMI) caused by conducted and radiated emission through a process of modifying the pulses from a pulse width modulation process. The present invention also increases the peak power levels which leads to increased efficiency. Conventional switching power supplies utilize continuous pulse width modulation (PWM) process. In contrast, the present invention modifies the pulses of the PWM process by separating the pulses of the PWM process into different groups. Moreover, the present invention modifies the pulses of the PWM process during a second half of the rectified waveform by shifting the start time of the pulses in a time domain. Resultantly, the spike energy of the waveform is distributed along the time domain. Additionally, the present invention increases the number of pulses of a waveform such that more power can be delivered to the output load as necessary.
By modifying the pulses of the PWM process, the present invention addresses a number of issues prevalent with the existing switching power supply circuits. As mentioned earlier, when large spikes occur as noise during switching, the noise gets conducted back to the AC input lines and also gets radiated into the air causing EMI. Therefore, an external filtering circuit is required to meet the electromagnetic compatibility (EMC) standards. More specifically, the present invention stops switching action during the charging phase of a capacitor and allows switching to occur only during the discharging phase of the capacitor. In doing so, the present invention blocks noise through a diode which also eliminates the need for a large and costly external filtering circuit.
Almost all switching power supplies use electrolytic capacitors which lose some of its capacitance with low temperatures. In particular, if the temperature drops below a certain value, the device the capacitor is being used on may not function to its fullest capabilities. Therefore, the need for a method which helps the device to function at its fullest capabilities at very low temperatures is clearly evident.
The objective of the present invention is to address the aforementioned issues. More specifically, the present invention introduces an application specific integrated circuit which reduces EMI and increases peak power level through pulse modification. In particular, the present invention has the ability to receive a discontinuous set of pulses and shift the start time of a series of pulses per cycle. Furthermore, the present invention has the ability to increase the number of pulses according to the load requirements. In a broader perspective, the present invention is small in size, which is beneficial when utilizing the present invention within a device. In contrast to traditional switching power supplies, the present invention provides minimum interference and higher peak power when used in a wireless circuit. Additionally, the present invention adjusts the working mode according to the temperature such that low temperatures have no effect on the overall functionality of the device the present invention is being used on.